Photographic colour material

ABSTRACT

A photographic light-sensitive material for the silver bleaching process which comprises on a support in at least one layer a quinoxaline of formula   WHEREIN A1 and A2 are each an alkyl-, aralkyl-, aryl, or heterocyclic group and n is 1 or 2, whereby the oxygen-containing ring is connected with the quinoxaline group in the 5,6- or 6,7position as a colour bleaching catalyst as well as quinoxalines of the formula given above are disclosed.

United States Patent [1 1 Schlunke et al.

Oct. 23, 1973 PHOTOGRAPHIC COLOUR MATERIAL [75] Inventors: Hans-PeterSchlunke, Marly-le-Petit;

Christian Egli, Magden, both of Switzerland [30] Foreign ApplicationPriority Data Sept. 4, 1970 Switzerland l325l/70 [52] U.S. Cl. 96/53,96/20 [51] Int. Cl G030 7/16 [58] Field of Search 96/53, 20, 99, 73

[56] References Cited UNITED STATES PATENTS 3,656,953 4/1972 Schlunke etal. 96/20 2,669,517 2/l954 Mueller 3,615,494 10/1971 Watanabe ct al96/53 Primary Examiner-Norman G. Torchin Assistant ExaminerRichard L.Schilling Attorney-Harry Goldsmith et al.

[57] ABSTRACT A photographic light-sensitive material for the silverbleaching process which comprises on a support in at least one layer aquinoxaline of formula O\ N Ar gN Az v 11 Claims, N0 DrawingsPHOTOGRAPHIC COLOUR MATERIAL This invention relates to photographicmaterial which contains quinoxalines as colour bleaching catalysts.

According to the present invention these is provided a photographiceight-sensitive material for the silver bleaching process whichcomprises on a support in at least one layer a quinoxaline of formula or6,7-position, as colour bleaching catalysts. Advantageously quinoxalinesof formula are used, wherein A and A each represent an alkyl group withat most 5 carbon atoms or an optionally substituted benzene group and nrepresents 1 or 2, whereby the rings are interconnected in the indicatedmanner.

Groups A, and A or A and A., as well as groups A; and A of the followingformula (3) can be the same or different. Alkyl groups with 1 m5,preferably 1 to-3 carbon atoms which can be used are e.g. amyl, n-sec.or tert. butyl, n or isopropyl, ethyl or in particular methyl groups. Asat most bicyclic aralkyl groups are mentioned e.g. the naphthenyl orbenzyl group. The at most bicyclic aryl groups are naphthalene, diphenylor benzene groups, having optionally further substituents such as, e.g.,lower alkyl, lower alkoxy, hydroxy, substituted amines, amine orhalogen. Particularly lower alkyl groups can be used as substituents forthe amine. Heterocyclic 5 or 6-membered groups which can be used are,e.g., pyridyl, furyl or thienyl groups.

Depending on whether n is l or 2 the compounds of formula (1) aredioxolo or dioxano quinoxalines.

Of particular interest are quinoxalines of formula wherein A and A eachrepresent a methyl or phenyl group and n is 1 or 2, whereby the ringsare interconnected in the indicated manner.

Among these quinoxalines those of formula 2 0\ N A (0H,).

\ N/ CHa and particularly of formula /0\ NICK; fln

\ N on,

wherein A is a methyl or phenyl group and n is l or 2, whereby the ringsare interconnected in the indicated manner, are particularly suitable.

The quinoxalines of formula (1) can be used as colour bleachingcatalysts in a processing bath, preferably in a colour bleaching bathand/or in a layer of the photographic material.

The reduction products of the quinoxalines of formula (1) can also beused for so-called bleach development, by themselves acting as hydrogendevelopers in an acid medium.

Such processes are known, e.g.,from French Pat. No. 1,565,800.

The quinoxalines of formula (I) can be used either alone or in thepresence of other conventional colour bleaching catalysts. It is alsopossible to use various quinoxalines of formula (1) simultaneously inthe colour bleaching bath. Finally the quinoxalines of formula (1 canalso be used together with other bleachingpromoting measures, e.g.,together with an irradiation or bubbling with a gas of the colourbleaching bath or in additon of organic solvents to the colour bleachingbath. 7 w

The quinoxalines of formula (1 can therefore be incorporated into acoating free from bleachable image dye. The multi-layer material cantherefore have for example an additional gelatin layer containing onlythe catalyst located directly on the emulsion carrier or between twocolour layers. In the latter case the catalystcontaining layer also actsas a separating layer. In addition, the catalyst can also beincorporated into colloidal silver or layers containing filter orantihalo dye or covering coatings. These filter layers as well as thecoatings with the image dyes advantageously contain gelatin as thelayers colloid.

However, the quinoxalines of formula l can also be incorporated directlyinto a layer containing image dye. Furthermore, the mjlti-layer materialcan have the conventional composition. Colour-photographic images can beproduced in per se known manner with the photographic materials of tjeindicated composition.

The colour bleaching catalysts of formula (I) can, as already indicated,e. g. be added to the colour bleaching bath where they then directlyexert their action. They can also be added to a previous treatment bath,e.g., the developer, a hardening bath, a stop bath or a special bathpreceeding the silver bleaching bath. In this way a certain portion ofthe catalyst quantity introduced is absorbed and retained by thephotographic coating material until it can act in the colour bleachingbath. Depending on the particular use the quantity of catalyst used canvary within wide limits. Generally it suffices for a strong action toadd 0.001 to 0. lg of catalyst to 1 litre of a colour bleaching bath ofnormal composition containing a silve complex constituent such as, e.g.,alkali metal bromide or iodide or thiourea and optionally ananti-oxidising agent such as e.'g. sodium hypophosphite and for givingthe necessary pH-value a stong organic or inorganic acid such as, e.g.,benzenesulphonic acid, hydrochloric acid, sulphuric acid, phosphoricacid or sodium bisulphate.

Further objects of the invention are therefore a photographic,light-sensitive material for the silver dyebleach process containing ona carrier in at least one layer as a colour bleaching catalyst aquinoxaline of formula 1 and photographic processing baths, particularlycolour bleaching baths, characterised in that as the colour bleachingcatalyst they contain at least a quinoxaline of formula (1).

A further object of the invention is a process for pro ducing colourphotographic images according to the silver dye-bleach process onmaterials containing on a substrate at least one silve halide emulsionlayer with a bleachable image dye by exposure, developing the silverimage and colour bleaching, characterised in that the colour bleachingis performed in the presence of at least one quinoxaline of formula (1)as the colour bleaching catalyst.

The hitherto known compounds used in the silver bleaching process ascolour bleaching catalysts have a widely different action on azo dyes ofdiffering constitution. Whereas they can be very effective with oneclass of azo dyes, they may have only a very slight bleaching-promotingaction with another class. Thus, there is a need for compounds whichalone or in combination bring about a uniform bleaching of all threelayer dyes of a multi-layer material.

it has been found that quinoxalines of formula (1) are admirably suitedfor this purpose. They are characterised by a very favourable positionof their redox potentials and good solubility in the colour bleachingbath in the requisite concentrations. Particularly if the groups A, andA of formula (1) each represent a methyl group the quinoxalinesaccording to the invention of formula (1) have a good activity and leadto a favourable gradation. In addition, when they are pres-.

ent and appropriately used bleach couplings between the individual imagedye-containing layers are largely eliminated.

Quinoxalines of formula (1) are appropriately prepared in per se knownmanner (cf J.C.E. Simpson, Condensed Pyridazine and Pyrazine Rings in A.Weissberger, The Chemistry of Heterocyclic Compounds, J. Wiley & Sons,New York, 1953, 203ff) by condensation of the corresponding aromatic1,2-diamine with a 1,2-dicarbonyl compound. Instead of diamine it ispossible to use the corresponding more stable nitroaniline or thecorresponding o-dinitro compound, which can be reduced to the desireddiamine and then without intermediate separation reacted to givequinoxaline. The corresponding benzofuroxans or their reduction products(benzofurazans) can also be reduced to 1,2-diamines via intermediatestages (F.B. Mallory S.P. varimbi, J. Org. Chem., 28, l656ff, 1963) andcondensed to quinoxalines.

Instead of the 1,2-dicarbonyl compound it is also possible to react ana-substituted halogeno ketone of formula wherein X is a nucleophilicgroup, e.g. -l, -Br, -Cl, or -Ol-l with the o-diamine to give thecorresponding 1,2- dihydroquinoxaline (J. Figueras, J. Org. Chem., 31,803ff, I966), which is then oxidised in situ to quinoxaline.

The quinoxalines are obtained in better yield and greater purity if thecondensation is performed under nitrogen.

a-Oximinoketones can also be reacted with 1,2- diamines to givequinoxalines (cf. J.C.E. Simpson, loc.

cit.).

As starting materials for one of the indicated syntheses can, e.g., beused the compounds given in the following table.

1,2-Dicarbonyl compounds, oz-halogenoketones, a-Oximinoketones diacetyl3-bromobutanone-2 3-chlorobutanone 3-iodbutanone 3-oximinobutanone-2hexandione-3 ,4

benzil benzoin bromodesoxybenzoin l-phenylpropandionel ,2l-phenyl-2-oximinopropanone-l bromopropiophenone chloropropiophenone 2'-hydroxypropiophenone di-(a-naphthyl )-diketone di-(B-naphthyl)-diketone a-pyridil y-pyridil di-( Z-thienyl )-diketone di-( 2-furyl)-diketone o-dinitrobenzenes, o-nitroanilines, 1,2-diamines[4,5-d]-dioxolol ,2-dinitrobenzene [4,5-d -dioxolol-amino-2-nitrobenzene [4,5-d ]-dioxolol ,2-diaminobenzene [3,4-dl-dioxolo-l ,Z-dinitrobenzene [3 ,4-d]-dioxolol-amino-2-nitrobenzene [3,4-d]-dioxolo-l-nitro-2-aminobenzene[3,4-d1-dioxolo-1 ,2-diaminobenzene [4,5-b]-dioxanol ,2-dinitrobenzene4,5-b] -dioxanol -amino-2-nitrobenzene [4,5-b]-dioxanol,2-diaminobenzene [3,4-b]-dioxano-l ,2-dinitrobenzene [3 ,4-b]-dioxanol-amino-2-nitrobenzene [3 ,4-b -dioxanol -nitro-2-aminobenzene[3,4-b1-dioxanol ,2-diaminobenzene benzofuroxans, benzofurazans[5,6-d]-dioxolobenzofuroxan [5,6-d]-dioxolobenzofurazan[4,5(6,7)-d]-dioxolobenzofuroxan [4,5-d]-dioxolobenzofurazan[5,6-b]-dioxanobenzofuroxan [5,6-b]-dioxanobenzofurazan[4,5(6,7)-b]-dioxanobenzofuroxan [4,5-b]-dioxanobenzofurazan Thequinoxalines of formula (1) are new and can serve as intermediates,e.g., in the preparation of pharmaceutically active compounds.

' The percentages in the following preparation instructions and examplesare percentages by weight.

Preparation Instructions General instructions An appropriate o-dinitroderivative is dissolved in a suitable solvent, e.g.,"methanol, ethanol,glacial acetic acidor dimethyl formamide or also only suspended with 1to percent by weight of hydrogenation catalyst e.g., a 10 percentpalladium-carbon catalyst and hydrogenated under normal pressure,optionally with initial heating. When the reaction is terminated thecatalyst isfiltered off under N and the filtrate under N is mixed withan at least equimolar quantity of distilled or recrystallised diketoneor a solution of the diketone in a suitable solvent, whereby in mostcases a colour deepening occurs and the temperature rises. Subsequentlythe mixture is refluxed until the end of the reaction and the desiredsubstance is isolated after cooling. The product can be purified byrecrystallising from a suitable solvent by distillation or if necessaryby chromatography or sublimation. Instead of the dinitro derivative itis possiblein some cases to use the corresponding o-nitroamino compound.If the o-diamino compound is single and obtainable with sufficientpurity it can be reacted directly or in the form of its salt(hydrochloride, hydrosulphate, hydroperchlorate, etc.) with thecorresponding diketone in a suitable solvent under nitrogen. When usinga salt it is recommended that an equivalent quantity of sodium orpotassium acetate be added to saturate the liberated acid.

For the synthesis of the 2,3-asymetrical compounds the a-diketone isreplaced by a-bromopropiophenone. The thus formed 1,2-dihydroquinoxalineis then oxidised with m-nitrobenzenesulphonic acid Na salt in thepresence of an aqueous sodium hydroxide solution to give quinoxaline. I

The redox potentials are determined in the usual manner by means ofpolarography. The solvent used is in all cases a mixture ofdimethylformamide-ZN sulphuric acid in a ratio of 1:1. The potential ismeasured relative to an Ag/AgCl electrode of known potential and thenconverted to the potential relative to a normal hydrogen electrode.Whereas in certain cases two single electron transitions, characterisedby that two polarographic waves are observed in other cases only onepolarographic wave is observed, corresponding to the average redoxpotential.

The melting points and analysis results of the quinoxalines of formula(1) are given in the table.

A [6,7-d]-dioxolo-2,3-dimethylquinoxaline g 94.5mmol) of[4,5-d1-dioxolol ,2- dinitrobenzene are dissolved in 200ml of methanoland after adding 1g of 10 percent palladium/animal charcoa hydrogenatedunder normal pressure, whereby the internal temperature rises to 60C;hydrogen consumption 14.1 litres 100 percent of theory. The catalyst isfiltered off under nitrogen and the filtrate is mixed with 8.6g(l00mmol) of diacetyl under N The reaction mixture is stirred for 45minutes at room temperature and then evaporated to dryness. Afterrecrystallising from a little methanol 15.7g (=84 percent of theory) ofcompound A are obtained, whereby the thin layer chromatogram intoluenezacetone 9:1 is uniform. The

IR spectrum and nuclear magnetic resonance spectrum conform with thestructure.

B [6,7-d]-dioxolo-2-methyl-3-phenylquinoxaline t 31.5g (l49mmol) of[4,5-d]-dioxolo-l ,2- dinitrobenzene are hydrogenated as described inExample A; H; consumption 21 litres 100 percent of theory. The filtrateis mixed with 15g of crystallised sodium acetate and 33.25g of freshlydistilled bromo-' propiophenone and refluxed for 3 hours. The hotsolution is mixed with a freshly prepared solution of 36.5 g of 95percent sodium-m-nitrobenzenesulphonate and 66g (1.45mol) of sodiumhydroxide in 287ml of H 0 and 45ml of ethanol and refluxed for 2 hours.After cooling overnight 300ml of water are added and the solutiondistilled to 500ml. The residue from which already part of the desiredproduct is precipitated is continuously extracted for 12 hours with500ml of ethyl acetate.

After treating the organic phase with animal charcoal and filtering, thesolvent is removed under reduced pressure. The residue is dissolved in aminimum of ethanol, again treated with animal charcoal and the filtrateagitated in 500ml of hot water. After slowly cooling to 0C., 8.7g (=22percent of theory) of compound B are finally obtained. The thin-layerchromatogram in to]- ueneracetone 9:1 reveals in addition to the mainquantity four slight impurities. The lR and NMR spectra show thecharacteristic strips for the required structure.

C [5,6-d]-dioxolo-2,3-dimethylquinoxaline 1. [4,5-dl-dioxolacetanilide51.4g (308mmol) of [4,5-d]-dioxolonitrobenzene are dissolved in 500ml ofethanol and hydrogenated in the presence of 1.5g of 10 percentpalladium/carbon under normal pressure at room temperature. Afterfiltering off the catalyst and evaporating the solvent there remain 41.1g (=95 percent of theory) of the amino compound as a brown oil which inthe thin-layer chromatogram with toluene2acetone 9:1 as the solventsystem reveals in addition to the main zone two small impurities. Thisoil is mixed with 44ml of glacial acetic acid and 35ml,of aceticanhydride and after adding 0.55g of zinc powder is refluxed for 1 hour.The still hot solution is poured onto 200ml of an ice-water mixture. Theresulting crystals are filtered off and dried at 60C in vacuo. Yield47.8 percent of theory (based on the nitro compound) of m.p. 134.1C. Thethin-layer chromatogram in trichloromethanezmethanol 9:1 as the solventsystem reveals a main spot, whilst the IR and NMR spectra show thestrips characteristic of the structure. 2.[4,5-d]-dioxolo-2,3-dinitroacetanilide 47.8g (266mmol) of[4,5-d]-dioxolacetanilide are added portionwise accompanied by virorousstirring at 10C. to a mixture of concentrated HNO (d=l.4) and 166ml offuming l-INO (d=1.54). On termination of the addition the reactionmixture is stirred for a further 10 minutes and then poured onto anice-water mixture. After neutralising the solution to pH=6 the aqueousphase is extracted with ethylacetate, the organic phases are driedtogether and the solvent removed under reduced pressure. The remainingyellow crystals (16g) are dissolved in a minimum of methanol and treatedwith activated charcoal. The filtrate is mixed with 1,000ml of thewater-ice mixture. The resulting yellow needles are suction filtered anddried;

7 yield 8.4g 11 percent of theory of m.p. 179.1C. The thin-layerchromatogram in toluenezacetone 6:4 reveals in addition to the main zonetwo negligible impurities. The IR and NMR spectra conform with thestructure. NMR spectra reveal the characteristic strips expected 3.[4,5-d]-dioxolo-2,3-dinitroaniline from the structure.

9.6g (35mmol) of [4,5-d]dioxolo2,3- D.[5,6-b]-dioxano-2,3-dimethylquinoxaline dinitroacetanilide are refluxedfor 3 hours in 40ml of 9.0g (40mmol) of [3,4-b]-dioxano-l,2- ethanol and4g of 37 percent hydrochloric acid. After dinitrobenzene, dissolved in250ml of ethanol are hycooling to 0C. 7.1g (=90 percent of theory) ofthe drogenated in the presence of Raney nickel (activity amine found tobe thin-layer chromatographically (sol- 5) and -5g of 1 Pe t pallaium/carbon at rOOm vent system toluene:acetone 7:3) uniform. The lR andtemperature and normal pressure; H, consumption NMR spectra show theabsorptions to he expected 5300ml 90 percent of theory. After filteringoff the from the structure, catalyst and adding 3.5m! (40mmol)ofdiucetyl the so- 4. [3,4-dl-dioxolo-l,2-dinitrobenzene l5 lution isrefluxed for 1 hour and evaporated to about 7.1 (3lmmol) of[4,5-(11-diQXOlO-2,3-dinitl'oaniline 50ml under reduced pressure. Theresidue is treated suspended in 215ml of glacial acetic acid arediazotised ith activated charcoal and the filtrate cooled to with 7.4g(l07mmol) of sodium nitrite in 70ml of 96 -l0C, whereby 2.9g 33 percentof theory of cOmpercent sulphuric acid at 15C. After stirring for 2pound D are obtained. The thin-layer chromatogram in hours at roomtemperature the reaction mixture is toluenezacetone 8:2 as the solventsystem reveals no poured into 142ml of ethanol. After adding 0.45g ofimpurities. The IR and NMR spectra conform with the copper powderstirring takes place at room temperastructure. ture with the end of gasevolution (3 hours). The reac- [6.7- ]-di0X n0- ,3- iphenylquinoxalinetion mixture is poured onto ice-water. On leaving to 9.0g (40mmol) of[4,5-bl-dioxano- 1,2- stand almost colourless needles are precipitated,which dinitrobenzene, dissolved in 250ml of ethyl acetate are aredissolved in a minimum of methanol and treated hydrogenated as describedunder D. The filtrate is with activated charcoal. After adding water4.7g (74 mixed with 8.4g (40mmol) of benzil and refluxed for 1 percentof theory) of slightly yellowish and fine needl s hour. After cooling toroom temperature the solvent is are obtained. The thin-layerchromatogram in tolueneremoved under reduced pressure, the residue istaken :acetone 7:3 reveals in addition to the main spot one P in 300 m1of acetone: tfichlol'omethane 1011, slight impurity. The IR and NMRspectra conform with treated with activated charcoal and finallyevaporated the structure. to about half the volume. After cooling to 0C.5.9g 5. [5,6-d]-dioxolo-2,3-dimethylquinoxaline 43 percent of theory) ofcompound E are obtained. 3.1 g (15 mmol) of [3,4-d]-dioxo1o-1,2- Thethin-layer chromatogram in toluenezacetone 9:] dinitrobenzene are, asdescribed in Example A, hydroreveals in addition to the desiredsubstance E an insiggenated in 50 ml of ethanol as the solvent. Afteradding nificant impuritY. The IR and NMR spectra conform 1.3g (15mmol)of diacetyl the reaction mixture is rewith the structure. fluxed for 1hour. The thus obtained residue is taken up The other compounds shown inTable I were prein 30ml of methanol, again treated with animal charparedanalogously to one of the hereinbefore described coal and finally cooledto -50C. Thereby lg (=33 perinstructions.

TABLE I In Formula (1) Analysis Connec- Melting Percent C Percent IIPercent. N

tion point, Compound A1 A2 73 point C. Cale. Found Cale Found Cale.Found 1 5.7 213.3 55.34 55.47 4.03 5. 03 13.35 13.05 1 5.7 125.2 72.7272.51 4.53 4.51 10.50 10. 43 1 5.5 154.5 55.34 55.52 4. 03 5.25 13.3513.02 2 5.5 141.3 55.55 55.53 5.50 5.54 12.05 12.34 2 5.7 225.0 77.5377.53 4. 74 4.77 3.23 3.04 1 5.7 152.7 77.20 77.43 4.32 4.44 3.53 3. 251 5.5 135.0 77.20 77.37 4 32 4.51 3.53 3.30 2 5.7 130.0 55.55 55.35 5.505.53 12.05 13.10 2 5.7 105.5 73.37 73.52 5.07 4.03 10.07 0. 00 2 5.5102.2 77.53 77.70 4.74 4.72 3.23 3.00

Example 1 Example 2 On a l3 X 18cm glass plate is cast a solution of3.3m] If instead of compound G compound Edissolved in of 6 percentgelatin, 2.0m] of a 1 percent solution of the dimethyl formamide isused, then proceeding as dehardener2,4-dichloro-6-phenylamino-l,3,5-triazinoscribed in Example 1 again aclean positive image of 3'-sulphonic acid, 0.5ml of a 2.10 molarsolution of 5 the exposed wedge is obtained. If instead of compoundcompound G in acetone and 4.2m] of water. After dry- G compound J isused as an acetic solution, then proing, on this is cast a solution of3.3m] of 6 percent gelaceeding as described in Example 1 once again aclean tin, 3.3m] of a silver bromide emulsion containing 5.3g positiveimage is obtained of the wedge used as the of silver per 100g ofemulsion, 2.0m1 of the above hardoriginal. ener, 0.3m! of a lpercentsolution of the blue-green dye l0 EXAMPLE of formula A photographicmaterial with three colour layers CmQ-Sm-NH on 002115 OH unmmQcn,

0 H058 SOaH (lCzHs HOaS S0:H

. r V n g (110) and 1.1m] of water. After drying the thus obtainedlamcontains on a white-opaque cellulose acetate film a redinar bond astep wedge is copied thereon (50 lux, 3 2o sensitive silver bromideemulsion with the blue-green sec.) and then the copy is developed asfollows: dye of formula Q-o 0-HN 0-orn on 1. develop for 6 minutes in abath containing per litre thereover an empty gelatin separating layerand then a 50g of anhydrous sodium sulphite, 0.2g ofl-phegreen-sensitive silver bromide emulsion with the purplenyl-3-pyrazolidone, 6g of hydroquinone, 35g of andye of formula hydroussodium carbonate, 4g of potassium bro- After a further separating layerfollows'a layer with a mide and 0.3g of benzotriazole; yellow filter dyeor colloidal silver acting as a yellow fil- 2. fix for 2 minutes with asolution of 200g of sodium ter, over which there is a silver bromidelayer with the thiosulphate, 10g of sodium sulphite, g of soyellow dyeof formula 7 H038 (|)-CH; HaC--O soar:

N=NQNHC OQ-C OHN -N=N H3O on:

I OIH HOa S (104) dium acetate and 10ml of glacial acetic acid per andacovering layer. All these layers are hardened with litre of water; ahalogenotriazine compound such as 2,4-dichloro-6- 3 rinse f 4 i tphenylamino-l,3,5-triazino-3'-sulphonic acid. 4. colour bleach for 6minutes with a solution of 10g This Copying material is successivelyexposed under of potassium iodide in 1 1m of lN -sulphuric acid; a StepWedge into the three Spectral areas blue (Kqdak 5 time for 2 minutesWratten filter 2B+49), green (Kodak. Wratten filter W t X29 d, 6. bleachthe remaining silver for 2 minutes with a g i d t an bath containing150ml of 37 percent hydrochloric escnbed m xamp e eve ope or minutes anfixed. Subsequently bleaching takes place in a silver 5g of uppersulphate and 30g of potasslum bleaching bath containing per litre 27mlof 96percent bromide per litre;

sulphuric acid, 10g of potassium iodide and 10ml of a rmse for 2 mmutes;4.10 molar solution of compound A in glacial acetic fix for 4 minutes asunder 5 acid. After a brief rinsing the remaining silver is, as de- 9.rinse for 10 minutes. scribed in Example 1 under (6), oxidised, rinsedand After drying the clean colourless bleached photofixed as describedabove. After thorough washing-out graph is obtained with a clearlygraduated gradation of and drying a white-bleached neutral wedge isobtained, the wedge used as the original. I opposite to the original inits gradation.

1 1 EXAMPLE 4 Instead of compound A as in Example 3, it is possible touse compound B or any other quinoxaline indicated in Table I dissolvedin a suitable photographically inactive, water-miscible solvent.Proceeding as described in Example 3, with appropriate balancing onceagain the positive-grey image of the original used, cleanly bleached onwhite at the corresponding points is obtained.

Example 5 A photographic material as described in Example 3 is as statedexposed into the three spectral areas. Subsequently the copy isdeveloped as follows:

1. develop for 7 minutes in a bath containing per litre 50 g ofanhydrous sodium sulphite, 0.2g of l-phenyl-3-pyrazolidone, 6g ofhydroquinone, 35g of anhydrous sodium carbonate, 4g of potassiumbromide, 0.3g of benzotriazole and 20ml of a 4.10 molar solution ofcompound C in acetone;

2. fix for 2 minutes with a solution of 20g of sodium thiosulphate, 10gof anhydrous sodium sulphite and 10ml of glacial acetic acid per litre;

3. rinse for 2 minutes;

4. colour-bleach for 10 minutes with a solution of 10g of potassiumiodide in 1 litre of sulphuric acid;

5. rinse for 2 minutes;

6. bleach the remaining silver for 8 minutes with a bath containing perlitre 150ml of 37 percent hydrochloric acid, 25g of copper sulphate and30g of potassium bromide;

7. rinse for 2 minutes;

8. fix for 3 minutes, as under 2);

9. rinse for 10 minutes.

After drying a neutral wedge is obtained with a clean white and clearlygraduated gradation.

Example 6 On a 13 X 18cm glass plate is cast a solution with thefollowing composition: 3.3ml of a 6 percent gelatin, 3.3ml of a silverbromide emulsion containing 5.3g of silver per 100g of emulsion, 1.0mlof a 1 percent solution of the hardener described in Example 1, 03ml ofa 1 percent solution of the blue-green dye of formula (101) and 2.1ml ofwater. After drying on the thus obtained layer is copied a step wedgeand the plate is then treated as follows:

I. develop for l minutes in a bath containing per litre 20g of anhydroussodium sulphite, lg of 4- methylaminophenolsulphate, 4g of hydroquinone,10g of anhydrous sodium carbonate, 2g of potassium bromide and 3g ofsodium thiocyanate;

2. rinse for 2 minutes;

3. oxidise for 2 minutes with a solution of g of potassium bichromateand 5ml of 96 percent sulphuric acid per litre of solution;

4. rinse for 4 minutes;

5. rinse for 5 minutes with a solution of 50g of anhydrous sodiumsulphite per litre;

6. rinse for 3 minutes;

7. develop for 4 minutes with a solution consisting of 2g of Calgon, 50gof anhydrous sodium sulphite, g of hydroquinone, 50g of anhydrous sodiumcarbonate, 2g of l-phenyl-3-pyrazolidone and 20 ml of a 1 percentt-butyl-aminoborane solution per litre:

8. rinse for 2 minutes;

9. colour bleach for 6 minutes with a colour bleaching bath containingper litre 27ml of 96 percent sulphuric acid, 10g of potassium iodide and10ml of a 4.10" molar solution of compound D in ethanol; l0. rinse for 2minutes; 1 l. bleach for 2 minutes of the residual silver as describedin Example 1 under 6); l2. rinse for 2 minutes; 13. fix for 4 minutes asdescribed in Example under l4. rinse for 10 minutes; After drying aclear, bleached colourless image of the wedge used with oppositegradation is obtained.

Instead of compound D it is possible to use compound C or anotherquinoxaline described in the table in a suitable photographicallyinactive, water-miscible solvent. Proceeding as described in thisexample, once again a clean bleached colourless image of the exposedwedge with opposite gradation is obtained.

Example 7 A solution consisting of 3.3ml of 6 percent gelatin, 3.3ml ofa silver bromide solution containing 5.3g of silver per 100g ofemulsion, 1.0m] of a 1 percent solution of the hardener described inExample I, 0.3m! of a 1 percent solution of the blue-green dye offormula (10]) described in Example 1, 0.5m] of a 4.10 molar solution ofcompound G in acetone and 1.6ml of water is cast on a 13 X 18cm glassplate. After drying on the thus obtained layer a step wedge is copied(50 lux, 10 sec.) and the copy processed further as described inExample 1. After drying a clean bleached colourless positive image isobtained of the wedge used as the original.

Example 8 A photographic material as described in Example 3 is, asdescribed in Example 3, exposed into the three spectral areas. The copyis then treated as follows:

1. develop 7 minutes in a bath containing per litre 20g of anhydroussodium sulphite, 10g of anhydrous sodium carbonate. 4g of hydroquinone,lg of 4-methylaminophenol-sulphate, 2g of potassium bromide and 10ml ofa 4.10 molar solution of compound G in acetone;

2. fix for 2 minutes with a solution of 200g of sodium thiosulphate, 15gof anhydrous sodium sulphite,

25g of crystallised sodium acetate and 13ml of glacial acetic acid perlitre;

3. rinse for 2 minutes;

4. colour bleach for 10 minutes with a solution containing 10g ofpotassium iodide, 27ml of 96 percent sulphuric acid and 5ml of a 4.10molar solution of compound G in acetone per litre;

5. rinse for 2 minutes;

6. bleach the remaining silver for 8 minutes, as described in Example 5under 6);

7. rinse for 2 minutes;

8. fix for 3 minutes as under 2);

9. rinse for l0 minutes.

After drying a clean, white bleached positive image of the original isobtained.

Example 9 On a 13 X 18cm glass plate is cast a solution of 3.3m! of 6percent gelatin, 2.0ml of a 1 percent solution of the hardener describedin Example 1, 3.3m] of a silver bromide emulsion containing per 100g ofemulsion, 5 .3 g of silver, 0.3m] of a 1 percent solution of theblue-green dye of formula (101) and 1.1m] of water. After drying, a stepwedge is copied thereon (501lux, 3 sec.) and the copy is treated asfollows:

develop for 6 minutes;

I fix for 2 minutes;

rinse for 4 minutes as described in Example 1;

colour bleach for 6 minutes with a solution containing per litre 27ml of96 percent sulphuric acid, 10g of potassium iodide and 10ml of a 4.10molarsolution of one of the compounds H or I in dimethyl formamide.

After rinsing for 2 minutes the remaining silver is oxidised asdescribed in Example 1 under 6), rinsed and fixed as describedhereinbefore. The copy is thoroughly washed and dried. In all cases, aclean bleached colourless blue-green wedge is obtained, whose gradationis parallel to the original.

Example 1.0

2.0m] of a 1 percent solution of the hardener described in Example 1,3.3ml of a silver bromide emulsion containing 5.3g of silver per 100g ofemulsion and 0.4m] of water is cast on a 13 X 18cm glass plate. Afterdrying a step wedge is copied thereon (50 lux, 5 sec.) and the copy istreated as follows:

Develop and fix as described in Example 1, colour bleach for 6 minuteswith a solution containing per litre 10g of potassium iodide, 27ml of96.percent sulphuric acid and 10ml of a 4.10 molar solution of compoundA, B, C or H in ethanol or in another suitable watermiscible,photographically inactive solvent. After briefly rinsing, the remainingsilver is oxidised as described hereinbefore, rinsed and fixed. Afterthorough washing-out and drying in all cases a clean bleached colourless image of the original used is obtained with a clearly graduatedgradation.

Example 1 l A 13 X 18cm glass plate is coated with a solution of 3.3m]of 6 percent gelatin, 2.0ml of a 1 percent solution of the hardenerdescribed in Example 1, 3.3m] of a silver bromide emulsion containing5.3g of silver per 100g of emulsion, 0.5m] of the yellow dye of formulaand 0.9m] of water. After drying a step wedge is copied thereon lux, 5sec.) and treated analogously to Examples 9 and 10, whereby instead ofthe compounds contained therein the colour bleaching bath contains 10mlof 4.10 molar solution of one of the substances B, F and .l in acetoneor another suitable, watermiscible photographically inactive solvent.After drying a clean bleached colourless yellow image of the originalused is obtained.

Example 12 On a photographic material as described in Example 10 a stepwedge is exposed (500 lux, 10 sec.). The strip is well moistened with alN-sulphuric acid containing 10 mo] of compound B per litre andsubsequently brought into close contact with a polished iron plate.After briefly rinsing, fixing takes place followed by thorough rinsing.After drying a silver wedge corresponding to the original and a colourwedge opposite wherein A, and A are each an alkyl group with at most 5carbon atoms, an at most bicyclic aralkyl group with 1 to 5 carbon atomsin the alkyl portion, an at most bicyclic aryl group or a 5 or6-membered heterocyclic group having as hetero atoms N, O or S, and n is1 or 2, whereby the oxygencontaining ring is connected with thequinoxaline group in the 5,6 or 6,7-position, as a colour bleachingcatalyst.

2. Photographic material according to claim 1, which comprises aquinoxaline of formula wherein A and A are each an alkyl group with atmost 5 carbon atoms, benzene, lower alkyl-benzene, lower alkoxy-benzene,hydroxybenzene, aminobenzene or halobenzene, and n is l or 2 as a colourbleaching catalyst.

3. Photographic material according to claim 2, which comprises aquinoxaline of formula Nj Ar N Au wherein A and A are each a methyl orphenyl group and n is l or 2 as a colour bleaching catalyst.

4. Photographic material according to claim 3, which comprises aquinoxaline of formula wherein A is a methyl or phenyl group and n is 1or 2 as a colour bleaching catalyst.

5. Photographic material according to claim 4, which comprises aquinoxaline of formula /o NIom (CHM:

\ N/ CH:

O\ N Ar (C41) I wherein A and A are each an alkyl group with maximum 5carbon atoms, an at most bicyclic aralkyl group with l to 5 carbon atomsin the alkyl portion, an at most bicyclic aryl group or a 5 or6-membered heterocyclic group having as hetero atoms N, O or S, and n isl or 2, whereby the oxygen-containing ring is connected with thequinoxaline ring in the 5,6 or 6,7- position as the colour bleachingcatalyst.

7. Process according to claim 6, characterised in that as the colourbleaching catalyst a quinoxaline of formula is used, wherein A and A areeach an alkyl group with maximum 5 carbon atoms, benzene, loweralkylbenzene, lower alkoxy-benzene, hydroxybenzene, aminobenzene orhalobenzene, and n is l or 2.

8. Process according to claim 7, characterised in that as the colourbleaching catalyst a quinoxaline of foris used, wherein A and A are eacha methyl or phenyl group and n is 1 or 2.

9. Process according to claim 8, characterised in that as the colourbleaching catalyst a quinoxaline of formula 0\ Nj/Ab (CHDD N cm is used,wherein A is a methyl or phenyl group and n is l or 2.

10. Process according to claim 9, characterised in that as the colourbleaching catalyst a quinoxaline of formula NICK! CH )n i N CH:

is used, wherein n is l or 2. 11. Process according to claim 6,characterised in that the quinoxaline is in the colour bleaching bath.

2. Photographic material according to claim 1, which comprises aquinoxaline of formula
 3. Photographic material according to claim 2,which comprises a quinoxaline of formula
 4. Photographic materialaccording to claim 3, which comprises a quinoxaline of formula 5.Photographic material according to claim 4, which comprises aquinoxaline of formula
 6. A process for producing a colour photographicimage by the silver dye-bleach process using a material which carries ona substrate, at least one silver halide emulsion layer with a bleachableimage dye, by exposing the material, developing the silver image andcolour bleaching the image dye in accordance therewith, characterised inthat the colour bleaching is performed in the presence of at least onequinoxaline of formula
 7. Process according to claim 6, characterised inthat as the colour bleaching catalyst a quinoxaline of formula 8.Process according to claim 7, characterised in that as the colourbleaching catalyst a quinoxaline of formula
 9. Process according toclaim 8, characterised in that as the colour bleaching catalyst aquinoxaline of formula
 10. Process according to claim 9, characterisedin that as the colour bleaching catalyst a quinoxaline of formula 11.Process according to claim 6, characterised in that the quinoxaline isin the colour bleaching bath.